1. Field of the Invention
The present invention relates to a rotating type variable resistor, and in particular, to a structure of a rotating type variable resistor employed for various controllers such as an electronic apparatus especially for the use in a vehicle.
2. Description of the Related Art
A structure of a rotating electric component such as a rotating type variable resistor and an encoder in the related art has a case having a hollow support member and a plurality of contact members (i.e. sliding contacts) embedded in a support unit, an axial member (i.e. rotating member) having a hollow axial unit and being rotatably supported by a case and having a conductive pattern formed in a rotating unit, and a mounting member (i.e. cover member) covering the top of the case (for example, see patent document 1).
Hereinafter, the structure of the rotating electric component of the related art will be described with reference to the accompanying drawings.
FIG. 6 is a cross-sectional view illustrating a rotating electric component of the related art, and FIG. 7 is a disassembled perspective view illustrating the rotating electric component.
Referring to FIGS. 6 and 7, the case 21 molded with a synthetic resin has a rectangular support unit 21b having a ring-shaped concave unit 21a, and a cylindrical support unit 21d having a penetrating hole 21c at its center and being perpendicular to the center of the support unit 21b, and a plurality of contact members 22 are embedded as a unit with the terminal in the support unit 21b of the case 21.
The axial member 23 molded with a synthetic resin has an axial unit 23b having a penetrating hole 23a at its center, and a ring-shaped rotating member 23c formed at the lower end of the axial unit 23b, and the axial unit 23b and the rotating member 23c are shaped as a unit, and the axial unit 23b is shaped like a cylinder having the same diameter throughout the length and thus a straight contour. And a conductive pattern 24 composed of a resistor or a code pattern is formed at the lower surface of the rotating member 23c, and an axial member 23 having the conductive pattern 24 inserts the support unit 21d to the penetrating hole 23a, and the rotating unit 23c is received within the concave unit 21a so that it is rotatably fitted in to the case 21.
A mounting plate 25 molded with a metal plate has a flat portion 25b having a hole 25a, a pair of legs 25c rectangularly bent from the flat portion 25b, and a plurality of mounting portions 25d rectangularly bent from the flat portion 25b, and the axial unit 23b and the support unit 21d are inserted to the hole 25a of the mounting plate 25 to allow the flat portion 25b to cover one surface of the rotating unit 23c, and a front end of the leg 25c is bent to the lower surface of the case 21 to allow the case 21 and the axial member 23 to fit together, and thus the mounting plate 25 has the functions of a mounting body and a case.
When a rotating electric component having the above-described configuration rotates the axial portion 23b of the axial member 23, the rotating unit 23c and the conductive pattern 24 rotate, and the contact piece 22 slides on and contacts with the conductive pattern 24, therefore an output signal is produced.
Further, the rotating electric component of such a configuration is mounted in a printed circuit board (not shown), and a push button switch 26 is disposed in the printed circuit board positioned within the penetrating hole 21c of the case 21 as shown in FIG. 6. And the support unit 21d of the case 21 and the axial portion 23b of the axial member 23 are cylindrical-shaped, so that another electric component can be disposed in the center space thereof, which yields an electric component having a good space factor.